Why Cordless Battery Tools Fail So Much

Lithium ion battery cells make many cordless tools possible: drills, reciprocating saws, circular saws, impact drivers. These batteries are getting so good, even nailers and lawn mowers are being powered by lithium-ion batteries.

The dark side is that these batteries are notorious for their high failure rates. And surprisingly enough, unlike ni-cad batteries, which fail in slow stages, lithium ion batteries fail all at one.

One minute they're working, the next minute they're not. You cannot revive them in any way. Disposal is the only answer.

Why does this happen and how can you prevent battery failure?

Failure: Frequently, Suddenly

My experiences with lithium ion batteries have convinced me that, at this stage, development still has a ways to go before these batteries will overtake the world of tools. Considering the proliferation of lithium ion in everything, my attitude may sound old-fashioned. But listen:

None of the batteries in my cordless tools have lasted more than a couple of years. Tools powered by ni-cad (nickel cadmium) batteries, though heavy and low-powered, are still going.

Is that acceptable? Let's say that two years is an acceptable lifespan for lithium ion batteries. What is unacceptable is when they fail far prior to that two year term--and so suddenly.

I have had cordless tools work one day, fail the next.

Unlike ni-cad, lithium ion batteries fail all at once, not slowly. Many of these have been rather new lithium ion batteries, too.

As it turns out, lithium ion batteries are like temperamental rock stars: they are overly sensitive and must be treated gingerly. If they go outside of their comfort zone, they refuse to play.

Because Failure Is Way Better Than Thermal Runaway

In short, lithium ion batteries have failure built into their design--as a safety precaution.

Lithium ion batteries, if they get too hot, can cause fires. The chance of this happening is extremely low. But stories of batteries catching on fire are so dramatic that they give the impression that lithium ion batteries are catching fire all the time.

The fancy term is thermal runaway. When a lithium ion battery strays outside its internal electrolyte low range of 158-194 degrees F, runaway occurs. The higher the juice in the battery, the faster the runaway. Runaway temps can soar to a blistering 1,110 degrees F.